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为揭示二元结构河岸的崩塌机理,本文采用荆江河岸原型土体为试验材料,开展了上、下荆江二元结构河岸崩塌过程的概化水槽试验,分析了河岸的崩塌过程、机理及崩塌后土体的堆积、分解和输移特点等.试验结果表明:平面滑动破坏在上荆江概化试验中发生频率最高,其崩塌过程包括岸顶竖向拉伸裂隙的出现以及崩塌土体(滑崩体)沿滑裂面的滑动两部分;下荆江概化试验河岸崩塌类型主要为悬臂破坏,发生机理为悬空土块宽度超过其临界值,自身产生的重力矩大于黏土层的抵抗力矩,从而绕中性轴旋转发生崩塌;从试验结果还可看出,上部黏性土层崩塌后大部分土体会暂时堆积在河岸坡脚处,不会被水流立即冲走,在一定时间内对覆盖的近岸河床起到一定保护作用;崩塌后土体在坡脚处呈三角形堆积,其坡度近似等于河岸水下稳定坡比或泥沙水下休止角;堆积土体的体积主要与崩塌土体体积有关,一般占后者的比例在0.38~0.74之间,实际计算中可以按照此比例进行估算.
In order to reveal the collapse mechanism of the bank of the binary structure, this paper adopts the prototype soil of Jingjiang River Bank as the experimental material to carry out the generalized flume experiment on the bank collapse process of the upper and lower Jingjiang dual structure, and analyzes the collapse process, mechanism and collapse Etc. The results show that the plane slip failure occurs most frequently in the general experiment of Shangjiang, and the collapse process includes the occurrence of vertical tensile cracks on the shore and the collapse of landslides Body) along the sliding surface of the sliding two parts; the lower Jingjiang generalized test river bank collapse is mainly the type of cantilever failure occurs because the suspended mass width exceeds its critical value, its own weight moment is greater than the clay layer of the resistance moment, so around It can also be seen from the test results that most of the soil will temporarily accumulate at the foot of the bank slope after collapse of the upper cohesive soil layer and will not be washed away immediately by the water flow. Shore river bed play a protective role; after collapse of the soil at the foot of the slope was a triangle accumulation, the slope is approximately equal to the river bank slope stability or sediment underwater slope angle; sediment body The plot is mainly related to the volume of the collapsed soil mass, generally accounting for the latter ratio of 0.38 ~ 0.74, the actual calculation can be estimated in accordance with this ratio.